Genome Analysis and Expression Patterns of Odorant-Binding Proteins from the Southern House Mosquito Culex pipiens quinquefasciatus

Olfactory-based behaviors in mosquitoes are mediated by odorant-binding proteins (OBPs). They form a multigenic family involved in the peripheral events in insect olfaction, specifically the transport of odorants to membrane-bound odorant receptors. OBPs contribute to the remarkable sensitivity of the insect's olfactory system and may be involved in the selective transport of odorants

Evolution of a Behavioral Shift Mediated by Superficial Neuromasts Helps Cavefish Find Food in Darkness

SummaryHow cave animals adapt to life in darkness is a poorly understood aspect of evolutionary biology [1]. Here we identify a behavioral shift and its morphological basis in Astyanax mexicanus, a teleost with a sighted surface-dwelling form (surface fish) and various blind cave-dwelling forms (cavefish) [2–4]. Vibration attraction behavior (VAB) is the ability of fish to swim toward the source of a water disturbance in darkness. VAB was typically seen in cavefish, rarely in surface fish, and was advantageous for feeding success in the dark. The potential for showing VAB has a genetic component and is linked to the mechanosensory function of the lateral line. VAB was evoked by vibration stimuli peaking at 35 Hz, blocked by lateral line inhibitors, first detected after developmental increases in superficial neuromast (SN) number and size [5–7], and significantly reduced by bilateral ablation of SN. We conclude that VAB and SN enhancement coevolved to compensate for loss of vision and to help blind cavefish find food in darkness

Mosaic hoxb4a Neuronal Pleiotropism in Zebrafish Caudal Hindbrain

To better understand how individual genes and experience influence behavior, the role of a single homeotic unit, hoxb4a, was comprehensively analyzed in vivo by clonal and retrograde fluorescent labeling of caudal hindbrain neurons in a zebrafish enhancer-trap YFP line. A quantitative spatiotemporal neuronal atlas showed hoxb4a activity to be highly variable and mosaic in rhombomere 7–8 reticular, motoneuronal and precerebellar nuclei with expression decreasing differentially in all subgroups through juvenile stages. The extensive Hox mosaicism and widespread pleiotropism demonstrate that the same transcriptional protein plays a role in the development of circuits that drive behaviors from autonomic through motor function including cerebellar regulation. We propose that the continuous presence of hoxb4a positive neurons may provide a developmental plasticity for behavior-specific circuits to accommodate experience- and growth-related changes. Hence, the ubiquitous hoxb4a pleitropism and modularity likely offer an adaptable transcriptional element for circuit modification during both growth and evolution

Tactical release of a sexually-selected pheromone in a swordtail fish

© The Authors, 2010. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e16994, doi:10.1371/journal.pone.0016994.Chemical communication plays a critical role in sexual selection and speciation in fishes; however, it is generally assumed that most fish pheromones are passively released since most fishes lack specialized scent glands or scent-marking behavior. Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization. However, it is unclear whether females are attending to passively produced cues, or to pheromones produced in the context of communication. We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni. Simultaneous-choice assays of mating preference showed that females attend to species- and sex-specific chemical cues emitted in male urine. Males urinated more frequently in the presence and proximity of an audience (conspecific females). In the wild, males preferentially courted upstream of females, facilitating transmission of pheromone cues. Males in a teleost fish have evolved sophisticated temporal and spatial control of pheromone release, comparable to that found in terrestrial animals. Pheromones are released specifically in a communicative context, and the timing and positioning of release favors efficient signal transmission.This work was funded by the National Science Foundation (www.nsf.gov), IOB-0447665

Sensorimotor Transformations in the Zebrafish Auditory System

Organisms use their sensory systems to acquire information from their environment and integrate this information to produce relevant behaviors. Nevertheless, how sensory information is converted into adequate motor patterns in the brain remains an open question. Here, we addressed this question using two-photon and light-sheet calcium imaging in intact, behaving zebrafish larvae. We monitored neural activity elicited by auditory stimuli while simultaneously recording tail movements. We observed a spatial organization of neural activity according to four different response profiles (frequency tuning curves), suggesting a low-dimensional representation of frequency information, maintained throughout the development of the larvae. Low frequencies (150–450 Hz) were locally processed in the hindbrain and elicited motor behaviors. In contrast, higher frequencies (900–1,000 Hz) rarely induced motor behaviors and were also represented in the midbrain. Finally, we found that the sensorimotor transformations in the zebrafish auditory system are a continuous and gradual process that involves the temporal integration of the sensory response in order to generate a motor behavior.Fil: Privat, Martin. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Romano, Sebastián Alejo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Pietri, Thomas. Centre National de la Recherche Scientifique; Francia. Inserm; FranciaFil: Jouary, Adrien. Champalimaud Centre For The Unknown; Portugal. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Boulanger Weill, Jonathan. Centre National de la Recherche Scientifique; Francia. Inserm; FranciaFil: Elbaz, Nicolas. Inserm; Francia. Centre National de la Recherche Scientifique; FranciaFil: Duchemin, Auriane. Centre National de la Recherche Scientifique; Francia. Inserm; FranciaFil: Soares, Daphne. New Jersey Institute of Technology; Estados UnidosFil: Sumbre, Germán. Centre National de la Recherche Scientifique; Francia. Inserm; Franci

Fish Geometry and Electric Organ Discharge Determine Functional Organization of the Electrosensory Epithelium

Active electroreception in Gymnotus omarorum is a sensory modality that perceives the changes that nearby objects cause in a self generated electric field. The field is emitted as repetitive stereotyped pulses that stimulate skin electroreceptors. Differently from mormyriformes electric fish, gymnotiformes have an electric organ distributed along a large portion of the body, which fires sequentially. As a consequence shape and amplitude of both, the electric field generated and the image of objects, change during the electric pulse. To study how G. omarorum constructs a perceptual representation, we developed a computational model that allows the determination of the self-generated field and the electric image. We verify and use the model as a tool to explore image formation in diverse experimental circumstances. We show how the electric images of objects change in shape as a function of time and position, relative to the fish's body. We propose a theoretical framework about the organization of the different perceptive tasks made by electroreception: 1) At the head region, where the electrosensory mosaic presents an electric fovea, the field polarizing nearby objects is coherent and collimated. This favors the high resolution sampling of images of small objects and perception of electric color. Besides, the high sensitivity of the fovea allows the detection and tracking of large faraway objects in rostral regions. 2) In the trunk and tail region a multiplicity of sources illuminate different regions of the object, allowing the characterization of the shape and position of a large object. In this region, electroreceptors are of a unique type and capacitive detection should be based in the pattern of the afferents response. 3) Far from the fish, active electroreception is not possible but the collimated field is suitable to be used for electrocommunication and detection of large objects at the sides and caudally

Molecular Characterization of the Gastrula in the Turtle Emys orbicularis: An Evolutionary Perspective on Gastrulation

Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance